Victoria's Department of Human Services (DHS) has admitted it failed to extend a protection order over three vulnerable children.

The children's grandmother has told the ABC she has now lost contact with the three young children, and she fears they are being exposed to a suspected paedophile.

The grandmother cannot be named to protect the identity of her grandchildren.

The woman claims she has repeatedly asked the department and the responsible minister for help to no avail.

She is speaking out because of what she says her grandchildren have been exposed to while in the care of their mother, and under the watch of the DHS.

The woman has three young granddaughters under the age of eight.

"I'm so scared of what's going to happen to them," she said.

"Violence, criminal activity, drugs; the little one - according to professionals - has already been sexually abused in some way.

"It's hard to take when she's only three."

The woman says her drug-affected daughter is not capable of caring for the three little girls, who have at times gone without food for days.

"That's why they came to me. The second time was [when] that little one had taken ecstasy tablets and that's why DHS had decided to get involved," she said.

But she says in April the child protection system failed in its most basic of responsibilities.

"I promised the girls I would get them help. I was in the car on the way to DHS when I got a phone call from the unit manager who said 'don't bother going to see them, we've just realised we forgot to go to court to get an extension on the order'," she said.

The woman says there was a further bungle with the department revealing to her daughter confidential complaints she had made.

"They said 'let's call it a clerical error'. I said 'let's call it negligence'," she said.

Other allegations

The woman has not seen her granddaughters for three months.

She believes they are regularly in the care of an extended family member she claims has been accused of child sex abuse.

She says DHS is aware of these allegations.

The Department of Human Services says it cannot comment on a case it is actively involved in.

A spokesman says DHS has clear procedures in conducting police checks, but he also admitted the department was at fault in not extending the protection orders.

The grandmother says she has approached Community Services Minister Lisa Neville and former police minister Bob Cameron for help but had no response.

She says there just are not enough child protection workers.

She says it is hard when a worker rings up at night and says "I don't have time, I've got more serious cases than this".

Opposition spokeswoman Mary Wolldridge says last year the Brumby Government lost 28 per cent of its child protection workers.

She says even if the state hires more, they will still quit at a high rate.

The grandmother says the words of her granddaughter keep haunting her.

"She said she wished she'd never been born because she was so sad," she said.

She says DHS told her she would need a lawyer to get custody of her granddaughters.

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